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You Asked, We Answered: Top 10 FAQs of 2020

USG has made a name for itself by creating high-quality construction materials that meet and exceed the performance expectations of our customers. Maintaining this reputation in the industry comes with the expectation of knowing your products inside and out.

One of the small ways we can nurture this is through the FAQ section of These frequently asked questions can ensure that our customers have the information needed to navigate the handling and installation of USG products without hassle. With that in mind, here are ten of the most popular FAQs from 2020:

10. What is the difference between wet-felted and cast ceiling panels?

Wet-felted panels are typically mechanically perforated and fissured. They are very dense and more economical than other types of ceiling panels. Cast ceiling panels are non-perforated and are manufactured in a different “cast” process (hence its name) that enhances their surface appearance and provides excellent sound absorption and durability.

9. What is the difference between Class A and Firecode® branded materials?

Class A fire rating signifies that a panel attained a flame spread index of 25 or less (out of 100) when tested in accordance with the Standard ASTM E84. Our Firecode® brand signifies that the panel has been classified as a protective membrane in a floor-ceiling or roof-ceiling assembly in accordance with the Standard ASTM E119. All Firecode® protective membranes offered by USG have attained a Class A rating.

8. Does silica-free joint compound exist?

There are no ready-mixed joint compounds that exist that are 100% “silica free.”  However, the amount of respirable crystalline silica in USG joint compounds is relatively low, headlined by Sheetrock Brand® Dust Control Joint Compound which was the first joint compound formulated to reduce airborne sanding dust.

7. What is the shelf life of plaster?

Plaster can be stored for 3-6 months if proper conditions are met. To ensure longevity, plaster should be stored in a cool, dry place protected from extreme heat & cold, direct sunlight, and at a temperature above 45°F (7°C).

6. Can USG Durock® Brand Cement Boards be used on the interior and exterior of buildings?

Yes, and they can also be used in below-grade applications like basements. However, this does not apply to direct ground-contact applications.

5. Do I need to add water when mixing Sheetrock® Brand UltraLightweight Joint Compound?

No, Sheetrock® Brand UltraLightweight Joint Compound is formulated as a ready-to-use product, so just simply mix and use. If you choose to add your own water to thin the mix, add clean water in half-pint increments, remix, and test apply until the proper consistency is achieved.

4. Can ready-mixed joint compound be used on exterior applications?

No, Sheetrock® Brand Joint Compounds like Durabond® and Easy Sand™ are only recommended to treat joints in interior gypsum ceiling board.

3. When comparing Sheetrock® Brand UltraLightweight Joint Compound to other joint compounds, is weight the only difference?

Weight is a major difference, but perhaps Sheetrock® Brand UltraLightweight Joint Compounds greatest feature on the jobsite is its workability. Improved slip makes it easier to both wipe down and work with hand tools—this product also has very good wet tack that holds tape in place securely. The ultralightweight and wet tack work together to prevent the compound from dripping, thus reducing the time required to clean compound off the floors.

2. How long does it take joint compound to dry?

Joint compound should fully dry in about 24 hours under ideal conditions (temperature of 70° with 70% humidity). Higher humidity coupled with lower temperatures will slow drying time—a simple touch test can determine if the material is still moist or damp, in which case more time is needed for it to dry completely.

1. Does it matter which side faces out when installing USG Durock® Brand Cement Board Panels with EdgeGuard?

It does not matter which side faces out. In fact, regardless of the side chosen, you can still expect the same performance with every installation. The purpose of having one smooth side and one textured side on USG Durock® Brand Cement Board allows for easy application of mastic (smooth side) and thin-set mortar (textured side). That said, mastic or thin-set mortar is suitable for either side of the board without compromising performance.